Halothane anesthesia for ambulatory dental patients

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RALOTEANE

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ANElTHESIA

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FOR AXBULATORY

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DENTAL PATIENT8

A. Del Pizza, M.D.,’ and A. Abella, D.D.S.,*+ New Haven, Conn. Deprtmemts

of Anesthesiology and Oral Surgery, !l’he Hospital of St. Raphael

the advent of general anesthesia in dental surgery, no ideal agent which S is safe, pleasant, and efficient has been found. Recently many drugs have been developed which may prove especially helpful in oral surgical procedures. INCE

One of these is halothane, an inhalation anesthetic developed in Great Britain. This agent was synthesized and investigated in studies on experimental animals in 1956 by Raventos, and in the same year it was administered clinically to 500 human patients by JohnstoneS Halothane (Fluothanc or 2-bromo-Zchloro-l,l,l-trifluorocthane) is a nonflammable liquid with a boiling point of 50.2O C. at 760 mm. of mercury. It is stable when properly stored and is nonexplosive. The oil-water solubility coefficient is 330, and there is a vapor pressure of 243 mm. Hg at 20° C. IIalothane does not react with soda lime. The drug is twice as potent as chloroform and four times more potent t.han ether (Table I). Halothane has a pleasant odor and is adminiskred primarily through special vaporizers, such as the Fluotce, to en%urc a consistent concentration of vapor. The induction time is short, as is the recovery time. Good muscular relaxation can be obtained reaclily rind with surprisingly small concentrations. The incidence of nausea and emcsis is reported to be low. Hypotension and bradycardia are often produced, but they usually respond to atropine, lightening of the plane of anesthesia, and t.he usual vasoprcssors. Realizing full well that dental anest.hcsiology is a separate art, requiring special agents and methods, WC attempted to test the feasibility and safety of halothane for the ambulatory unpremcdicated patient undergoing outpatient dental procedures. MATERIAL

AX’D

YE’L’HODS

Forty procedures were pcrformcd w a total of t.hirty-five patients selected from our outpatient dental clinic. The eighteen malt and seventeen female *Chief Resident, Department of Anesthesiology. **Chief Resident. Department of Oral Surgery. 1444

HALOTHANE

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TABLE ETHER Diethyl

TYPO Chemical formula Molecular weight Boiling point (degrees C. ) SDecifiC Eravitv*liquid -@vat&-l) Solubility iu 100 Dart8 water Soiubility oil-water 37O c. Limits of flammability Air

ether

c$4~p

I.

ANESTHESIA

Pwa~car

1445

PROPERTIES

VINETHENE Divinyl-ether

)

HALOTHANE

0HLoROFORW Chlorinated hydrocarbon

HgK$pd

CF,CHBrCI

qioyro

CHCI,

197.39

28.3

34.6

)

119.39

50.2

61.26

0.713

0.774

1.86

1.49

7.5

4.0

0.345

0.822

3.2

41.3

330

e::o7

Nonflemmable with 0,

1.85-36.5

100

0.5-50.0 1.85 A5 --

2.10-82.0 Vapor

tension

at

20° C. (mm. Hg)

233

439

ranged in age from 4 to 59 years, with the greatest number under 19 years of age (Table II). In each case a complete blood count and a urinalysis were performed during the week prior to surgical intervention, and each patient had a complete physical examination and chest x-ray within a period of six months prior to the surgical procedure. The patients were considered to be status l-2, according to the American Society of Anesthesiology standards. The same operator and anesthesiologist attended all the patients in order to keep variation in technique to a minimum. In addition to the operator and the anesthesiologist, two nurses assisted with the necessary retraction, suctioning, and blood pressure and pulse monitoring. All patients were accompanied to the outpatient department by a responsible second person. The operative procedures were carried out in the morning, so as to keep the fasting schedule from the previous evening aa short as possible. Atropine, the only premeditation given, was administered fortyfive minutes before the operation in doses ranging from 0.1 to 0.6 mg., according to the patient’s age and body weight. Each patient was asked to void prior to the operative procedure. The patients were treated in a manner duplicating the management of patients in a private practice of dentistry. They were seated in a standard patients

TBBLE AGE (YEAES) o- 9 10-19

20-29 30-39 40-49 50-59

II.

AGE DISTRIBUTION

OF THIRTY-FIVE

NO, OP PATIENTS

PATIENTS NO. OX’ PROCEDURES

13

13

11

11

5

6

:

1”

1

1

dental chair, with a body strap across the waist, and the chu.ir was adjusl~ed 1.0 a semireverse Trendelenburg position. The blood l~cssur~~, pulse rate, and rhythm were monit.ored in t.hc l)reoplbrat.ivc period, dnri tlg the pro~d1~~, and in the recovery phase. Notations were mado of the respiratory rate, rhythm, and such complications as excitement. during inductiorl? breath-holding, coughing, increased secretions, laryngospasm, retching, and vomiting. Elcctrocardiographic monitoring was done at random on approximately one-third of the patients, while electroenccphalographic correlation1u was performed on one-fourth of the patients. Anesthesia was induced with a face mask utilizing a flow of 3 liters of nitrous oxide per 1.5 liters of oxygen with 0.5 per cent halothane through a Fluotec Mark II vaporizer gradually increased to a maximum of 2 to 3 per cent concentration within two to five minutes, using a semiclosed carbon dioxide absorption apparat.us. When induction was completed, the face mask was replaced by a nasal mask attached 60 a nonrebreathing apparatus. The flow rate was adjusted to 6 liters of nitrous oxide per 2 liters of oxygen, with a halothane maintenance range of 0.5 to 2 per cent vapor. A bite block and a throat pack were inserted before the operation was begun. The procedures ranged from sinplc tooth extractions to multiple tooth extractions with alvcolectomy a.nd suturing. Upon completion of the procedure, the bite block was removed and the operative area was covered with pressure packing, after which 100 per cent. oxygen was administered by a face mask for a period of one to three minutes. The patient was allow-cd to recover consciousness in the dental chair and then had to stand alone or with minimal arm support in order to sit in a wheel chair. Hc was wheeled to the recovery room, approximately 50 feet from the dental room, and helped to a bed, where he remained under the constant surveillance of a qualified recovery room nurse. Each patient was discharged after he was judged by the operator or anesthesiologist to be fully recovered. He was then instructed to resume normal activity gradually, to keep an accuratcl record of any disagreeable symptoms that appeared within forty-eight hour postoperatively, and to return in one week for a checkup. RESULTS

In the series presented, it was noted that halothane was an excellent but precarious anesthetic agent for USCin oral surgical procedures on the ambulatory patient. The induction was pleasant and rapid, and the average induction time calculated for the forty procedures was 3.54 minutes (Table III). The average maintenance period of anesthesia was 5.48 minutes, with a total average anesthesia time of 9.03 minutes. Halothane afforded excellent relaxation in a short period of time. The relaxation was satisfactory enough that frequently the surgeon did not even make use of a bite block, and in all casesthe bite block was inserted only after induction of anesthesia was completed. On no occasion was a muscle relaxant necessary.

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HALOTHANE TABLE III.

ANESTHESIA

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AVERAGETIME FORDIFFERENT PHASES OF PMCEDURE

Indnction-3.54 minutes Maintenauced.48 minutes Total anesthesia time-g.03 minutes Recovery time 1. Primary (period from end of operation to point at which patient was able to answer questions coherently)-2.64 minutes 2. Secondary (period beginning from point at which patient was transferred to wheel chair until able to leave recovery room)-10 to 12 minutes

During induction, only one patient in the series had a mild laryngospasm, and this was easily corrected by the administration of positive-pressure oxygen via a breathing bag (Table IV). Coughing, retching, and vomiting during induction occurred in one case each, and there were five cases of induction excitement, three cases of breath-holding, and two cases OSincreased secretions. TABLE

Iv.

Dwhg induotitm period Breath-holding coughing Increased secretions Partial laryngospaam Inadequate airway Excitement Vomiting Retching During maintenance Arrhythmias Tachycadiaa Bradycardias Blood pressure decrease Blood pressure increase

CObiPLICATIONS

3 ; i 5 i

t 7 7 4

The major problem in the beginning of our study arose in the improper posterior placement of the throat pack which caused an obstruction of the airway and prevented the delivery of an adequate concentration of the anesthetic to the patient. Therefore, on three occasions anesthesia had to be reinduced to allow the surgeon to complete the necessary surgical procedures. This inadequacy was later remedied by a more anterior placement of the packing. During the constant electrocardiographic monitoring, it was noted that six patients in the series had arrhythmias consisting of premature auricular beats, premature ventricular beats, Q-T interval prolongation, nodal rhythm, nodal escapewith a wandering pacemaker, aberrant conduction, and ventricular tachycardia (Figs. 1 to 5). All arrhythmias were corrected by lightening the level of anesthesia and by delivering 100 per cent oxygen to the patient until a normal pattern appeared. Tachycardias (over 100 beats per minute) were noted in eight patients, whereas true bradycardias (below 60 beats per minute) were noted in seven patients. Interestingly enough, one patient in our series who was noted on two occasions to have premature ventricular beats and bigeminy returned for a third

1448

Fig. l.-Typical tied

electrocanliograPllic J. l3., sgrcl 10 years.

and clect~ot~n~cel~halographic rt?sponses to halothane. Idcad III. Drrmedicnted !\‘ith l,‘?OO ~1’. ;G.ropintt.

l’a-

visit and was given promcthaxinc (Phenergan) with at ropinc prcoperatively on the premise that the phenot.hiazincs “ trilquiliz!c ’ ’ the hcartL1 and thus prevent cardiac arrhythmias. This did not hold tl*uc in OLW patient,, for she developed an aberrant conduction, bigeminy, and a ventricular tachycardia on the third occasion (Figs. 5.4 and 523).

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Number 12

Fig. 2.-Klectrocardiograms correlating ele;d;eyphalogram. operatively.

RALOTHANE

showing Patient

ANEElTHESIA

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response of Q-T prolongation to halothane. v pith M. G., aged 25 years. given l/150 gr. z&opine r me-

DEL

PIZZO

hN1)

ABEIdLA

Fig. 3.-Electrocardiographic manifestation of abekant conduction with 3 per cent halothane and reversion to normal sinus rhythm with 100 per cent oxygen. Patient T. I<., aged 38, 1.eati II. given l/150 gr. atropine preoperatively.

Electroencephalographic monitoring done at random showed that only light levels of anesthesia were attained, even when electrocardiographic aberrations were noted. Our blood pressure monitoring proved that only seven patients in the series had a blood pressure drop of greater than 25 per cent of their original systolic levels. None of t.hese cases required t,he use of a vasopressor agent, although on one occasion intravenous atropinc was administered. Surprisingly enough, four patients under 19 years of age manifested a blood pressure rise of greater than 25 per cent of their systolic levels. Complications seen during the first twenty-four hours postoperatively consisted of six casesof headache, most of which responded to analgesics; five cases TAESE V. ---. ----

POSTOPERATIVE COMPLICATIONS . . --. _-... .-. .- ._..- -.--_.----.-__ --.. - .--_ __ .-.-_ .--

After 64 hours

Within 64 how-s Headache Disorientation Dizziness NtLUSes, vomitiug

Retching crping

(i 2 1 2

! 3

2 1

_.-

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ANESTBESIA

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HALOTHANE

ANESTHESIA

of vomiting (including one case in which a mother ilcadvertontly ;~l.lowcd 11~1. child to have fluids preoperaativcly) ; two cases ot na~wt:;l; two of: rlisoricutation, which lasted no more than twenty minutes; one case oi dizziness; one of retching; and three of crying. The only significant complications that persisted beyond twenty-four hours were headache (two cascsj and nausea (one case) (Table V). DISCUSSION

The potency of halothane as an inhalation agent for outpatient dental work appears to have no equal at this time. Certainl.y, the present-day use of nitrous oxide or trichloroethylene in dental offices leaves much to be desired. The use of intravenous drugs, such as thiopental sodium, methohexital sodium, hydroxydione (Viadril) , to name just a few in use today, always presents: the problems of individual dosage, cumulative effects of the drug, individual variation in response, and length of recovery secondary to metabolic breakdown of the agent by the body.4 In our series, multiple tooth extractions with alveolectomy and suturing were performed as a single procedure. The induction period was exceptionally short, and the mandibular muscle relaxation afforded was excellent. There were few stormy inductions, and these usually occurred in persons who were extremely agitated preoperatively and who developed arrhythmias during the procedure. It certainly would have been interesting to measure the preoperative and operative catecholamine levels in these patients in order to evaluate the possible correlation of the level of catecholamine rise with the severity of the arrhythmia noted. Halothane proved especially useful for pediatric patients, especially for children of the recalcitrant type. The necessity of venipuncture was dispensed with, as wa+t~ the necessity of using a muscle relaxant. All patients were well oxygenated, and complete control of the concentration of the agent delivered to the patient was regulated by the Fluotec vaporizer and by random electroencephalographic control. The surgeon was able to work in a relaxed atmosphere and to use any necessary equipment, since this agent is not flammable or explosive. Halothane offers the dental surgeon the advantage of working in an office atmosphere with an anesthetic agent of a potency usually relegated to the operating room. This obviates the necessity of performing many exodontia procedures in the hospital and, especially in child patients, secondarily diminishes the problem of psychic trauma which often accompanies hospitalization. On no occasion did any patient consider the administration of halothanc unpleasant. The total anesthesia time averaged 9.03 minutes per procedure, with the longest individual period of anesthesia lasting twenty-four minutes. We believe that this potent agent should not bc used for outpatient surgical procedures requiring more than thirty minutes, but other investigat.ors3 have used it for longer operations. The major physiologic disadvantage of halothane is its ability to decrease In all probability, this is aided by the the threshold of cardiac irritability.

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increased norepinephrine excretion in the apprehensive, unpremeditated patient. Therefore, halotilane anesthesia should be well monitored, which necessitates the availability of personnel trained in its use, experienced in the management of any possible complications, and able to resuscitate patients if necessary. The maintenance of an adequate airway is an ever-present problem in oral surgery. Packs, debris, and blood are always present in the operative field, and a poor airway leads to poor maintenance levels of anesthesia, not to mention the hazards of inadequate ventilation wit.h subsequent hypoxia. CONCLUSIONS

Halothane, a nonexplosive,. volatile anesthetic, was used as the principle ’ agent in forty oral surgical procedures in out-patients ranging in age from 4 to 59 years. This potent agent, however, offers as many disadvantages as advantages to the oral surgeon. In the present series we noted full well the rapid, smooth induction of anesthesia, the ease of maintenance, the rapid reversibility of action, the good muscular relaxation, and the rapid recovery which followed the administration of halothane. This agent, however, does have the disadvantage of being so potent as to cause arrhythmias a.nd cardiovascular and/or respiratory depression. Therefore, it should not be used by the unskilled anesthetist, and on no occasion should it be given without adequate clinical monitoring of the patient and without the availability of adequate means of resuscitation. The authors wish to express their appreciation to Dr. M. L. Garofalo and his associates without whose cooperation this investigation could not have been accomplished. REFERENCES

1. Johnstone, M.: Human Cardiovascular Response to Fluothane, Brit. J. Anesth. 28: 392, 1956. 2. Cole, Witt J.: The Use of Halothane-N,O for OPD Dental Work, M. J. Australia 47: 209, 1960. 3. &dove, Id. 8.: Halothane in Dental Anesthesia, J. Am. Dent. A. 60: 733, 1960. 4. Via, W. F., Jr., and Beyer, H. A.: New Developments in Anesthesiology, J. Am. Dent. A. 58: 18, 1959. 5. Driseoll, E. J., Christenson, G. R., and White, C. L.: Physiologic Studies in General Anestheaul for Ambulatory Dental Patients, OML SURQ.,ORAL MED. & ORAL PATH. 12: 1496, 1959. 6. Ausherman, H. M., and Adan, A. : Fluothane: A Preliminary Report, South. Id. J. 62: 46, 1959. 7. Stephen, C. R., and others: Clinical Experience With Fluothane, Anesthesiology 19: 2, 1958. 8. Dobkin, A. B.: Circulatory Dynamics During Light Halothane Anesthesia, Brit. J. Anesth. SO: 568, 1958. 9. Given, J. B., Little, D. Id., Jr., and Tovell, R. M.: Heart Sounds During Fluothane Anesthesia, Canad. Anaesth. Sot. J. 4: 3, 1957. 10. Gain, E. A., and Pale@ 8. 0.: An Attempt to Correlate the Clinical Signs of Fluothane Anesthesia With the EEG Levels, Canad. Anaesth. Sot. J. 4: 3, 1957. 11. Nelsen, R. M.: Tranquilization of the Heart With Ataractic Drugs, J. Thoracic Burg. 38: 610. 1959. 12. Dixon, G. D., and Matheson D. I.: Fluothane and Other Nonexplosive Halogenated Hydrocarbons in Clinicd Anesthesia, Canad. Id. A. J. 79: 365, 1958. 13. Robson, J. G., and Sheridan, G. A.: Preliminary Investigation With Fluothane, Anesth. & Analg. 38: 62, 1957.